1. Field of the Invention
The present invention relates to a control apparatus configured to control an image forming system configured to form a color image and a transparent image on a sheet, a program that causes an information processing apparatus or an information processing system to operate as the control apparatus, a recording medium that records the program, and an image forming system.
2. Description of the Related Art
Recently, it is desired by the printing market to improve the quality of a print product by increasing the degree of glossiness of a designated area. More specifically, it is desired to raise the level of glossiness of a designated area to a level higher than the level of glossiness of other areas.
In order to meet the demand by the market, Japanese Patent Application Laid-Open No. 04-338984 discusses an image forming apparatus that uses a transparent toner. The image forming apparatus discussed in Japanese Patent Application Laid-Open No. 04-338984 forms a transparent toner on an area whose glossiness is to be increased.
More specifically, the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 04-338984 serially applies color toners (e.g., yellow, magenta, cyan, and black color toners) and a transparent toner onto a sheet and then collectively fixes the color and transparent toners formed on the sheet. Accordingly, the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 04-338984 can raise the level of glossiness of the designated area to a level higher than the level of glossiness of other areas.
While it is desired to improve the quality of a print product, it is also highly desired to increase the productivity of a print product. In order to increase the productivity of a print product, it is useful to increase the speed of conveying a sheet. If the speed of conveying a sheet is increased, the amount of heat that a conveyed sheet receives from a fixing device may decrease. If a sheet receives a small amount of heat, then it is necessary to reduce the amount of toner to be fixed on the sheet.
Accordingly, if color toners and a transparent toner are collectively fixed on a sheet as in the method discussed in Japanese Patent Application Laid-Open No. 04-338984, the amount of heat applied to a sheet is relatively small in relation to the total amount of toners. In this case, fixing failure may occur.
In order to solve the above-described problem, Japanese Patent Application Laid-Open No. 2008-139589 discusses a method for coping with a small amount of heat applied on a sheet, in forming a transparent toner on the entire surface of a sheet, by separately executing processing for fixing color toners and processing for fixing a transparent toner.
The image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2008-139589 transfers and fixes color toners on a sheet before transferring and fixing a transparent toner on the sheet having the color toners fixed thereon. Accordingly, the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2008-139589 can reduce the amount of toner fixed on the sheet at a time.
As described above, if the amount of heat which the fixing device can apply on a sheet is small, it is useful to separately execute color toner fixing processing and transparent toner fixing processing. If any other fixing method is used, the amount of toner that can be collectively fixed on a sheet may decrease if the speed of conveying a sheet is increased.
On the other hand, the level of glossiness of a designated area cannot always be increased if a transparent toner is partially formed as discussed in Japanese Patent Application Laid-Open No. 4-338984 by using the method discussed in Japanese Patent Application Laid-Open No. 2008-139589.
More specifically, if a transparent toner is formed on a designated area, whose glossiness is to be increased, of a sheet having color toners fixed thereon and the formed transparent toner is fixed on the sheet, then the level of glossiness of the area on which the transparent toner is formed may decrease. To paraphrase this, it was found that if a transparent toner is formed on a designated area, whose glossiness is to be increased, of a sheet having a high-density image, such as a photographic image, and if the formed transparent toner is fixed after that, then the level of glossiness of the area on which the transparent toner is fixed may decrease.
In addition, if an image is formed on a high-glossiness sheet (a sheet having a high level of glossiness), such as a gloss coated paper, the level of glossiness of an area on which the transparent toner is fixed may decrease regardless of the density of color images. As a result, in the above-described cases, the conventional methods cannot raise the level of glossiness of a designated area.